"A radio built like this, with individual subsystems connected together, is much more understandable."

Yes! this has been my experience too, building something from first principles and given some tools and direction to experiment you get the chance, and experience, to really learn. I've been looking for resources like this for building amps but they're either small signal or the whole design. You understand how they work but not where and what to change if you wanted to tinker or build your own.